1. Field of the Invention
The present invention relates to retro-reflective markers for image-guided surgery.
2. Related Art
Systems for obtaining coordinates of a point or points of interest include marker-tracking systems. Such marker-tracking systems typically rely on objects having one or more markers affixed thereto. The markers that are affixed to the object may be active markers (e.g., light-emitting diode markers), passive markers (e.g., retro-reflective markers) or a combination of active and passive markers. In a medical application context, such as image-guided surgery, a user (e.g., a doctor) touches the surface of interest (e.g., a surface of a patient's body) using the distal tip of an object (e.g., a probe or a surgical instrument). A marker-sensing device (e.g., a pair of cameras) views the marker(s) affixed to the object. On the basis of the known locations of the cameras and the location(s) of the marker(s) as seen by each camera, such systems calculate the three-dimensional coordinates of the marker(s). Then, on the basis of the known relationship between the location(s) of the marker(s) and the location of the object tip, the marker-tracking system determines the coordinates of the object's tip. With the object's tip on the surface, those coordinates also correspond to the coordinates of the surface at that point.